'\" et
.TH UUX "1P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
uux
\(em remote command execution
.SH SYNOPSIS
.LP
.nf
uux \fB[\fR-jnp\fB] \fIcommand-string\fR
.fi
.SH DESCRIPTION
The
.IR uux
utility shall gather zero or more files from various systems, execute a
shell pipeline (see
.IR "Section 2.9" ", " "Shell Commands")
on a specified system, and then send the standard output of the command
to a file on a specified system. Only the first command of a pipeline
can have a
.IR system-name !
prefix. All other commands in the pipeline shall be executed on the
system of the first command.
.P
The following restrictions are applicable to the shell pipeline
processed by
.IR uux :
.IP " *" 4
In gathering files from different systems, pathname expansion shall
not be performed by
.IR uux .
Thus, a request such as:
.RS 4 
.sp
.RS 4
.nf

uux "c99 remsys!\(ti/*.c"
.fi
.P
.RE
.P
would attempt to copy the file named literally
.BR *.c
to the local system.
.RE
.IP " *" 4
The redirection operators
.BR \(dq>>\(dq ,
.BR \(dq<<\(dq ,
.BR \(dq>|\(dq ,
and
.BR \(dq>&\(dq 
shall not be accepted. Any use of these redirection operators shall
cause this utility to write an error message describing the problem
and exit with a non-zero exit status.
.IP " *" 4
The reserved word
.BR !
cannot be used at the head of the pipeline to modify the exit status.
(See the
.IR command-string
operand description below.)
.IP " *" 4
Alias substitution shall not be performed.
.P
A filename can be specified as for
.IR uucp ;
it can be an absolute pathname, a pathname preceded by ~\c
.IR name
(which is replaced by the corresponding login directory), a pathname
specified as ~/\^\c
.IR dest
(\c
.IR dest
is prefixed by the public directory called
.IR PUBDIR ;
the actual location of
.IR PUBDIR
is implementation-defined), or a simple filename (which is prefixed
by
.IR uux
with the current directory). See
.IR "\fIuucp\fR\^"
for the details.
.P
The execution of commands on remote systems shall take place in an
execution directory known to the
.IR uucp
system. All files required for the execution shall be put into this
directory unless they already reside on that machine. Therefore, the
application shall ensure that non-local filenames (without path or
machine reference) are unique within the
.IR uux
request.
.P
The
.IR uux
utility shall attempt to get all files to the execution system. For
files that are output files, the application shall ensure that the
filename is escaped using parentheses.
.P
The remote system shall notify the user by mail if the requested
command on the remote system was disallowed or the files were not
accessible. This notification can be turned off by the
.BR \-n
option.
.P
Typical implementations of this utility require a communications line
configured to use the Base Definitions volume of POSIX.1\(hy2017,
.IR "Chapter 11" ", " "General Terminal Interface",
but other communications means may be used. On systems where there are
no available communications means (either temporarily or permanently),
this utility shall write an error message describing the problem and
exit with a non-zero exit status.
.P
The
.IR uux
utility cannot guarantee support for all character encodings in all
circumstances. For example, transmission data may be restricted to 7
bits by the underlying network, 8-bit data and filenames need not be
portable to non-internationalized systems, and so on. Under these
circumstances, it is recommended that only characters defined in the
ISO/IEC\ 646:\|1991 standard International Reference Version (equivalent to ASCII) 7-bit range
of characters be used and that only characters defined in the portable
filename character set be used for naming files.
.SH OPTIONS
The
.IR uux
utility shall conform to the Base Definitions volume of POSIX.1\(hy2017,
.IR "Section 12.2" ", " "Utility Syntax Guidelines".
.P
The following options shall be supported:
.IP "\fB\-j\fP" 10
Write the job identification string to standard output. This job
identification can be used by
.IR uustat
to obtain the status or terminate a job.
.IP "\fB\-n\fP" 10
Do not notify the user if the command fails.
.IP "\fB\-p\fP" 10
Make the standard input to
.IR uux
the standard input to the
.IR command-string .
.SH OPERANDS
The following operand shall be supported:
.IP "\fIcommand-string\fR" 10
.br
A string made up of one or more arguments that are similar to normal
command arguments, except that the command and any filenames can be
prefixed by
.IR system-name !.
A null
.IR system-name
shall be interpreted as the local system.
.SH STDIN
The standard input shall not be used unless the
.BR '\-' 
or
.BR \-p
option is specified; in those cases, the standard input shall be made
the standard input of the
.IR command-string .
.SH "INPUT FILES"
Input files shall be selected according to the contents of
.IR command-string .
.SH "ENVIRONMENT VARIABLES"
The following environment variables shall affect the execution of
.IR uux :
.IP "\fILANG\fP" 10
Provide a default value for the internationalization variables that are
unset or null. (See the Base Definitions volume of POSIX.1\(hy2017,
.IR "Section 8.2" ", " "Internationalization Variables"
for the precedence of internationalization variables used to determine
the values of locale categories.)
.IP "\fILC_ALL\fP" 10
If set to a non-empty string value, override the values of all the
other internationalization variables.
.IP "\fILC_CTYPE\fP" 10
Determine the locale for the interpretation of sequences of bytes of
text data as characters (for example, single-byte as opposed to
multi-byte characters in arguments).
.IP "\fILC_MESSAGES\fP" 10
.br
Determine the locale that should be used to affect the format and
contents of diagnostic messages written to standard error.
.IP "\fINLSPATH\fP" 10
Determine the location of message catalogs for the processing of
.IR LC_MESSAGES .
.SH "ASYNCHRONOUS EVENTS"
Default.
.SH STDOUT
The standard output shall not be used unless the
.BR \-j
option is specified; in that case, the job identification string shall
be written to standard output in the following format:
.sp
.RS 4
.nf

"%s\en", <\fIjobid\fR>
.fi
.P
.RE
.SH STDERR
The standard error shall be used only for diagnostic messages.
.SH "OUTPUT FILES"
Output files shall be created or written, or both, according to the
contents of
.IR command-string .
.P
If
.BR \-n
is not used, mail files shall be modified following any command or
file-access failures on the remote system.
.SH "EXTENDED DESCRIPTION"
None.
.SH "EXIT STATUS"
The following exit values shall be returned:
.IP "\00" 6
Successful completion.
.IP >0 6
An error occurred.
.SH "CONSEQUENCES OF ERRORS"
Default.
.LP
.IR "The following sections are informative."
.SH "APPLICATION USAGE"
This utility is part of the UUCP Utilities option and need not be
supported by all implementations.
.P
Note that, for security reasons, many installations limit the list of
commands executable on behalf of an incoming request from
.IR uux .
Many sites permit little more than the receipt of mail via
.IR uux .
.P
Any characters special to the command interpreter should be quoted
either by quoting the entire
.IR command-string
or quoting the special characters as individual arguments.
.P
As noted in
.IR uucp ,
shell pattern matching notation
characters appearing in pathnames are expanded on the appropriate local
system. This is done under the control of local settings of
.IR LC_COLLATE
and
.IR LC_CTYPE .
Thus, care should be taken when using bracketed filename patterns, as
collation and typing rules may vary from one system to another. Also
be aware that certain types of expression (that is, equivalence
classes, character classes, and collating symbols) need not be
supported on non-internationalized systems.
.SH EXAMPLES
.IP " 1." 4
The following command gets
.BR file1
from system
.BR a
and
.BR file2
from system
.BR b ,
executes
.IR diff
on the local system, and puts the results in
.BR file.diff
in the local
.IR PUBDIR
directory. (\c
.IR PUBDIR
is the
.IR uucp
public directory on the local system.)
.RS 4 
.sp
.RS 4
.nf

uux "!diff a!/usr/file1 b!/a4/file2 >!\(ti/file.diff"
.fi
.P
.RE
.RE
.IP " 2." 4
The following command fails because
.IR uux
places all files copied to a system in the same working directory.
Although the files
.BR xyz
are from two different systems, their filenames are the same and
conflict.
.RS 4 
.sp
.RS 4
.nf

uux "!diff a!/usr1/xyz b!/usr2/xyz >!\(ti/xyz.diff"
.fi
.P
.RE
.RE
.IP " 3." 4
The following command succeeds (assuming
.IR diff
is permitted on system
.BR a )
because the file local to system
.BR a
is not copied to the working directory, and hence does not conflict with
the file from system
.BR c .
.RS 4 
.sp
.RS 4
.nf

uux "a!diff a!/usr/xyz c!/usr/xyz >!\(ti/xyz.diff"
.fi
.P
.RE
.RE
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "Chapter 2" ", " "Shell Command Language",
.IR "\fIuucp\fR\^",
.IR "\fIuuencode\fR\^",
.IR "\fIuustat\fR\^"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "Chapter 8" ", " "Environment Variables",
.IR "Chapter 11" ", " "General Terminal Interface",
.IR "Section 12.2" ", " "Utility Syntax Guidelines"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
